This invention relates to production equipment for oil and gas wells, and more particularly to a subassembly for suspending a production tubing string to accomodate safety-related equipment in the wellhead.
Exploitation of underground petroleum deposits located beneath the ocean is most often accomplished by drilling and completing oil and gas wells from a fixed platform, wherein operations are performed similarly to those conducted on land. The man made platform provides the structure on which a drilling rig is mounted to drill the well and subsequently is the terminus of the casing strings and the wellhead assemblies. During production all producing operations and equipment are located on such a structure. Operationally, many similarities between land and platform operations exist but because of space limitations that exist on a platform it is normal that a multiplicity of wells will be sited to improve the cost effectiveness of platform drilling and completion. The need to provide additional safety devices in platform completions has led to the installation of down hole safety valves, surface safety valves and other safety techniques that are well recognized.
Recently, in an effort to further increase the safety of drilling and producing offshore platform wells, an additional safety device has been postulated, a shear ram blowout preventer (BOP) installed below the tubing head to provide a means of shearing the tubing and sealing the tubing string in event of a blowout. It would be the intent of this procedure to install the shear ram BOP on each well on the platform, suitably manifolded to hydraulic control systems which automatically operate in the event of a fire or a blowout. Only the well in which such an event occurs would be affected and the flow of fluids would be sealed.